Back to EveryPatent.com
United States Patent |
5,668,884
|
Clair, Jr.
,   et al.
|
September 16, 1997
|
Enhanced concert audio system
Abstract
A audio enhancement system and method of use with a sound system for
producing primary sound from at least one main loudspeaker located at a
main position. The audio enhancement system comprises at least one
wireless transmitter, time delay circuitry, and plural augmented sound
producing subsystems. Each sound subsystem is a portable unit arranged to
be carried by a person located remote from the main loudspeaker and
includes a wireless receiver and an associated transduce device, e.g., a
pair of stereo headphones. The transmitter broadcasts an electrical signal
which is representative of the electrical input signal provided to the
main loudspeaker. The broadcast signal is receiver by the receiver and is
demodulated and amplified to drive the transducer so that it produces
augmented sound substantially in synchronism with the sound arriving from
the main loudspeaker. To achieve that end the time delay circuitry delays
the electrical signal which is provided to the transducer for a
predetermined period of time corresponding generally to the time period it
takes for the primary sound to propagate through the air from the main
loudspeaker to the remote location at which the person is located.
Inventors:
|
Clair, Jr.; Roy Barry (Lititz, PA);
Borthwick; Ronald D. (Manheim, PA)
|
Assignee:
|
Clair Bros. Audio Enterprises, Inc. (Lititz, PA)
|
Appl. No.:
|
380511 |
Filed:
|
January 30, 1995 |
Current U.S. Class: |
381/82; 381/79 |
Intern'l Class: |
H04B 003/00 |
Field of Search: |
381/79,80,77,82
|
References Cited
U.S. Patent Documents
2567431 | Sep., 1951 | Halstead.
| |
3235804 | Feb., 1966 | McIntosh.
| |
4165487 | Aug., 1979 | Corderman | 381/79.
|
4610024 | Sep., 1986 | Schulhof.
| |
4618987 | Oct., 1986 | Steinke et al.
| |
4829500 | May., 1989 | Saunders.
| |
4899388 | Feb., 1990 | Mlodzikowski et al.
| |
4993074 | Feb., 1991 | Carroll.
| |
5058169 | Oct., 1991 | Temmer.
| |
5131051 | Jul., 1992 | Kishinaga et al.
| |
Foreign Patent Documents |
2006116 | Dec., 1969 | FR.
| |
55-077295 | Jun., 1980 | JP.
| |
57-202138 | Dec., 1982 | JP.
| |
9205673 | Apr., 1992 | WO.
| |
Other References
Dan Popescu, "Sound Reinforcement Systems in Early Danish Churches,"
Journal of the Audio Engineering Society, vol. 28, No. 10, Oct. 1980, pp.
713-717.
Popescu, Dan "Sound Reinforcement Systems in Early Danish Churches,"
Journal of the Audio Eng. Soci. Oct. 1980 vol. 28, No. 10. 713-717.
|
Primary Examiner: Kuntz; Curtis
Assistant Examiner: Lee; Ping W.
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis, L.L.P.
Parent Case Text
This application is a continuation of application Ser. No. 08/213,136,
filed Mar. 15, 1994, now U.S. Pat. No. 5,432,858, which is a continuation
of U.S. application Ser. No. 07/922,448, filed Jul. 30, 1992, abandoned.
Claims
We claim:
1. An audio enhancement system comprising:
at least one main electro-acoustic transducer for generating a primary
sound in response to a first electrical signal;
transmission means for converting said first electrical signal into a
transmission signal and for wirelessly transmitting said transmission
signal;
at least one personal electro-acoustic transducer unit, said at least one
personal electro-acoustic transducer unit including
at least one auxiliary electro-acoustic transducer having a low maximum
output sound level, wherein said maximum output sound level can be heard
by people only within a range of several feet of said auxiliary
electro-acoustic transducer in ambient sound, and
a receiver for receiving and converting said transmission signal into a
second electrical signal, said at least one auxiliary electro-acoustic
transducer generating an augmenting sound in response to said second
electrical signal; and
delay means for delaying at least one of said first and said second
electrical signals by a period of time substantially equal to an amount of
time required for said primary sound to reach said at least one personal
unit, such that said augmenting sound augments said primary sound to
enhance audio perception by at least one user within said range of said at
least one auxiliary electro-acoustic transducer, wherein said transmission
means transmits said transmission signal via a single predetermined
channel, wherein said at least one personal electro-acoustic transducer
unit includes said delay means for delaying said second electrical signal
by a period of time substantially equal to an amount of time required for
said primary sound to reach said at least one personal unit.
2. An audio enhancement system according to claim 1, wherein said delay
means comprising an adjustment means for permitting adjustment said period
of delay time.
3. An audio enhancement system according to claim 2, wherein said
adjustment means of said delay means includes a manual adjustment means
for permitting an audience member to manually adjust said period of delay.
4. An audio enhancement system comprising:
at least one main electro-acoustic transducer for generating a primary
sound in response to a first electrical signal;
transmission means for converting said first electrical signal into a
transmission signal and for wirelessly transmitting said transmission
signal; and
at least one personal electro-acoustic transducer unit, said at least one
personal electro-acoustic transducer unit including
at least one auxiliary electroacoustic transducer having a low maximum
output sound level, wherein said maximum output sound level can be heard
by people only within a range of several feet of said electro-acoustic
transducer in ambient sound,
a receiver for receiving and converting said transmission signal into a
second electrical signal, said at least one auxiliary electro-acoustic
transducer generating an augmenting sound in response to said second
electrical signal, and
delay means for delaying said second electrical signal by a period of time,
said delay means further comprising an automatic adjustment means for
automatically adjusting said period of time to be substantially equal to
an amount of time required for said primary sound to reach said personal
unit, such that said augmenting sound augments said primary sound to
enhance audio perception by at least one user within said range of said
auxiliary electro-acoustic transducer.
5. An audio enhancement system according to claim 4, wherein said
electro-acoustic transducer unit can be carried in a single human hand.
6. A method of enhancing audio sound, said method comprising the steps of:
generating a primary sound in response to a first electrical signal;
converting said first electrical signal into a transmission signal;
wirelessly transmitting said transmission signal;
providing at least one personal electro-acoustic transducer unit, said at
least one personal electro-acoustic transducer unit including at least one
auxiliary electro-acoustic transducer having a low maximum output sound
level, wherein said maximum output sound level can be heard by people only
within a range of several feet of said electro-acoustic transducer in
ambient sound, and a receiver;
receiving and converting in said personal unit said transmission signal
into a second electrical signal;
generating in said at least one auxiliary electro-acoustic transducer an
augmenting sound in response to said second electrical signal; and
delaying at least one of said first and said second electrical signals by a
period of time substantially equal to an amount of time required for said
primary sound to reach said at least one personal unit, such that said
augmenting sound augments said primary sound to enhance audio perception
by at least one user within said range of said at least one auxiliary
electro-acoustic transducer, wherein said transmitting step includes
transmitting said transmission signal via a single predetermined channel,
said method including the further step of delaying said second electrical
signal in said at least one personal electro-acoustic transducer unit by a
period of time substantially equal to an amount of time required for said
primary sound to reach said at least one personal electro-acoustic
transducer unit.
7. An audio enhancement method according to claim 6, further comprising the
step of permitting adjustment of said period of delay.
8. An audio enhancement method according to claim 6, further comprising the
step of permitting an audience member to manually adjust said period of
delay.
Description
The present invention generally relates to audio systems and more
particularly to systems for enhancing the sound received by audiences
located at varying distances from loudspeakers.
The current state of the art for sound production or sound supporting
equipment used in concert halls or in other spaces entails the use of one
or more main loudspeaker cluster locations. These are typically located
near the physical location of the actual sound source or that of the
virtual sound source. Unfortunately nature has provided some impediments
for these types of sound systems. In this regard as the sound produced by
the loudspeakers travel over distance, distortion of the frequency and
time spectrum naturally occur. Also, non-linear type distortions are
introduced due to the physics of the air compression and rare fractions by
which the sound propagates. Moreover, since the perceived loudness and the
sound pressure level decreases with increasing distance from the sound
source, in order to achieve the desired sound pressure level (SPL) at
remote listener positions substantially more sound pressure must be
developed at the source. However, increasing the sound pressure level
thereat produces more distortions. Thus, the larger the distance from the
sound source to the audience the more acute the problem.
Persons attending concerts in large halls or arenas are becoming more
demanding in their desires for high quality sound; they want to have the
sound quality delivered to them by public address speaker systems
approaching recording studio quality. This places a heavy burden on the
large sound system designer. One common approach to achieve that end is
utilize what has been referred to as "delayed speaker systems" in
combination with the main loudspeaker system. In particular, additional
loudspeakers are provided at remote locations so that they can be located
closes to some of the audience than the main loudspeaker(s) or cluster(s).
These fixed remote loudspeakers typically have their input signals delayed
in time with respect to the signals provided to the main
loudspeaker(s)/cluster(s) to synchronize their acoustic output with that
arriving from the main loudspeaker(s) or cluster(s).
In an article appearing in the Journal Of The Audio Engineering Society,
Vol. 28, No. 10, October 1980, entitled Sound Reinforcement Systems In
Early Danish Churches, by Dan Popescu, there are disclosed distributed
loudspeaker systems making use of remotely located loudspeakers and delay
equipment to synchronize the amplified sound with the direct (e.g., live)
sound.
Other approaches for delivering audio to persons within an auditorium are
found in the following U.S. Pat. Nos. 2,567,431 (Halstead), 3,235,804
(Mcintosh), and 4,165,487 (Corderman).
While the foregoing approaches to sound enhancement have some aural
benefits, they never the less still leave much to be desired from the
standpoint of delivering very high quality sound to the remote listeners.
Moreover, such systems can become relatively complex, unwieldy and
inflexible.
Accordingly, a need exists for an audio enhancement system which overcomes
the disadvantages of the prior art.
OBJECTS OF THE INVENTION
It is a general object of this invention to provide an audio enhancement
system which overcomes the disadvantages of the prior art.
It is a further object of this invention to provide an audio enhancement
system for providing augmented sound to persons located at remote
distances from main loudspeaker(s) or cluster(s) so that the augmented
sound is synchronized with the sound arriving from the main
loudspeaker(s)/cluster(s).
It is still a further object of this invention to provide an audio
enhancement system for providing augmented sound via personal transducers
to persons located at remote distances from main
loudspeaker(s)/cluster(s).
It is yet a further object of this invention to provide an audio
enhancement system for providing augmented sound via portable equipment to
persons using that equipment located at remote distances from main
loudspeaker(s)/clusters(s).
It is yet a further object of this invention to provide an audio
enhancement system for providing augmented sound via wireless transmission
to portable equipment used by persons located at remote distances from
main loudspeaker(s)/cluster(s).
SUMMARY OF THE INVENTION
These and other objects of this invention are achieved by providing an
audio enhancement system and method of use with a sound system producing
primary sound from at least one main loudspeaker located at a first
position. The primary sound is produced by the main loudspeaker in
response to an electrical input signal and is propagated through the air
to remote locations, at least one of which is arranged to have a person
thereat.
The audio enhancement system comprises transmitter means, time delay means,
and augmented sound producing means. The transmitter means is arranged for
effecting the wireless transmission of transmission signal to the
augmented sound producing means. The augmented sound producing means
produces augmented sound at remote location substantially in time
synchronization with the primary sound arrival so that said person
perceives the primary and augmented sounds in as a single enhanced sound
arrival. The augmented sound producing means comprises receiver means
receiving the transmission signal and for providing an electrical signal
in response thereto, and transducer means for converting the electrical
signal into the augmented sound. The time delay means is arranged to
effect the delay of the electrical signal to the transducer means for a
predetermined period of time corresponding generally to the time period it
takes for the primary sound to propagate through the air from the main
loudspeaker to the remote: location.
The method of this invention entails enhancing the sound provided to at
least one person located at a first location remote from at least one main
loudspeaker. The method comprises providing the person with a portable
sound augmentation system comprising a transducer device for providing
augmentation sound to that person, providing a main loudspeaker at a first
position, providing an audio electrical signal from an audio source for
producing primary sound from the loudspeaker in response thereto, and
wirelessly transmitting a transmission signal corresponding to the audio
electrical signal to the portable sound augmentation system, whereupon the
sound augmentation system provides an output electrical signal to the
transducer device to produce the augmentation sound at the remote
location. The provision of the output electrical signal to the transducer
device is delayed by the system for a predetermined period of time
corresponding generally to the time period it takes for said primary sound
to propagate to said remote location, whereupon said augmentation sound
and said primary sound reach the ears of the person in substantial
synchronism.
DESCRIPTION OF THE DRAWING
Other objects and many attendant features of this invention will become
readily appreciated as the same becomes better understood by reference to
the following detailed description when considered in connection with the
accompanying drawing Wherein:
FIG. 1 is a block diagram showing one embodiment of the audio enhancement
system of this invention;
FIG. 2 is a block diagram showing a portion of a second embodiment of the
audio enhancement system of this invention; and
FIG. 3 is a block diagram showing a portion of a third embodiment of the
audio enhancement system of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to various figures of the drawing wherein like reference
numerals refer to like parts, there is shown at 20 in FIG. 1, one
embodiment an audio enhancement system for use with a sound reproduction
system 22. The sound reproduction system 22 can be any type of system
having at least one main loudspeaker or at least one main cluster of
loudspeakers 23 located at one position, e.g., a stage, for producing
sound, e.g., music, in response to an electrical input signal provided by
any suitable audio source 24, e.g., an electronic stereo amplifier. The
main loudspeaker(s) or cluster(s) propagate the sound produced thereby
through the air so that it may be heard by persons located at various
positions, e.g., in plural rows of seats, located remote from the main
loudspeaker(s) or clusters.
The audio enhancement systems of this invention serve to augment or enhance
the sound heard by those persons by providing "augmentation sound" via
personal transducer devices which are located adjacent, e.g., carried or
worn, by those persons. To ensure that the augmentation sound enhances
rather than degrades or confuses the "main" arriving sound, i.e., the
sound arriving from the main loudspeaker(s) or cluster(s) the system of
this invention is arranged so that the augmentation sound arrives at the
listener's ears in time synchronism with the main arriving sound.
As will be appreciated by those skilled in the art from the descriptions to
follow the implementation of audio enhancement systems in accordance with
the teachings of this invention may take various configurations. Three
such configurations or embodiments are shown and described herein.
However, these embodiments are merely exemplary. Thus, other
configurations may be constructed in accordance with the teachings of this
invention. The three exemplary configurations or embodiments of this
invention will be described in detail later. Suffice it for now to state
that they comprise: a "zone" system shown in FIG. 1, a "manually
synchronized" system, a portion of which is shown in FIG. 2, and a
"self-synchronized" system, a portion of which is shown in FIG. 3.
Each of the embodiments of the audio enhancement basically comprises at
least one transmitting subsystem and at least one remote
receiver/transducer subsystem. Those subsystems will be described in
detail later. Suffice it for now to state that each receiver/transducer
subsystem basically comprises a receiver/amplifier compactly housed as a
portable unit, and an associated portable transducer device, e.g., a pair
of headphones, a portable speaker system, etc.
Each receiver/transducer subsystem is arranged to be located at any remote
location inhabited by a listener so that it may receive electrical signals
transmitted from the transmitting subsystem. The signals broadcast by the
transmitter subsystem(s) represent(s) the signals provided by the audio
source to the main loudspeaker(s) or cluster(s). The receiver/amplifier
unit of the subsystem serves to receive the broadcast signals and to
convert, process and amplify them into signals for driving the associated
transducer device, e.g., headphones, to produce the augmentation sound in
synchronism with the main arriving sound.
Moreover, as will be described in detail later and as mentioned earlier,
each of the receiver/transducer subsystems of this invention preferably
embodies the use of audio gear or equipment of the size normally used
personally or by small groups. Thus, a relatively large number of such
subsystems can be used for various types of sound enhancement
applications.
In order to facilitate locating a receiver/transducer subsystem as near as
possible to the listener, the electrical signal provided to it is
preferably transmitted without wire. Thus, the systems make use of
wireless transmitters in the transmitting subsystems (also to be described
later) for broadcasting the audio signals to the plural remote
receiving/transducing subsystems. Since wireless transmission also enjoys
some degree of locational freedom, this feature of the audio enhancement
system of this invention also allows the remote receiver/amplifier units
and the associated transducer devices to be in the form of hand
transportable equipment. In accordance with one preferred aspect of this
invention the location of the remote receiver/amplifier unit and its
associated transducer device is preferably made as close as possible to
the listener, to thereby reduce to a minimum real world physical problems.
Referring now to FIG. 1 the "zone" audio augmentation system 20 will now be
described. Before describing its details a brief overview of the system is
in order. To that end the system of FIG. 1 is designed for applications
wherein the audience is broken into discrete zones. Each zone encompasses
a predefined physical area located a knowndistance from the main sound
source, i.e., the main loudspeaker(s) or cluster(s). The system is
designed so that each listener located within a given zone receives
augmentation sound from his/her associated receiver/transducer subsystem
delayed a predetermined time after the production of the main sound by the
main sound source. Accordingly, the augmentation sound and the main sound
arrive at the ears of each listener within that zone in substantial
synchronism. In particular, the electrical signal that is destined for
each zone is delayed, optionally processed (as will be described later),
and transmitted on a discrete wireless channels to the receiver/transducer
subsystems in the various zones. Audience members within each zone then
tune their receiver to the appropriate channel for their zone to listen to
the sound produced by the associated remote transducer(s) in substantial
synchronism with the main arriving sound.
As will be appreciated by those skilled in the art since persons located
within a given zone will necessarily be located at different distances
from the main sound source there will inherently be some small time
arrival errors between the main arriving sound and the augmentation sound
for some persons within that zone. However, such errors can be minimized
by providing as large a number of zones as is practical. In so doing one
should be able to minimize, if not practically eliminate, sound arrival
timing errors. Practically the number of zones will be determined by a
trade off between allowable time arrival errors and the additional costs
of more zones.
As shown in FIG. 1 the enhancement system 20 basically comprises a
plurality of N dedicated transmitter subsystems, namely, 30-0, 30-1, and
30-N, and a plurality of respective, receiver/transducer subsystems 32-0,
32-1, and 32-N. These respective transmitter and receiver/transducer
subsystems are coupled to each other via "N" transmission channels. In
particular, each channel is arranged to carry the electrical signal
representing the signal from the audio source 24, but delayed by a
respective predetermined period of time with respect to the signal from
the audio source 24. The amount of delay established is a function of the
distance separating the main sound source from the associated remote zone
so that the main sound and the augmentation sound arrive at the listener's
ears substantially in synchronism. In the embodiment shown herein three of
the N channels, namely, channels 0, 1, and N, are specifically shown. It
should be understood that the number of channels in the system represents
the number of zones to established in the arena or concert hall.
In order to delay the audio signals by the desired amounts for each of the
N zones in the system the right (R) and left (L) outputs of the audio
source 24 are provided by respective lines 34R and 34L to a plurality (N)
time delay circuits 36-0, 36-1, and 36-N of a time delay unit 36. In a
preferred embodiment of this invention the time delay unit 36 is a digital
delay, e.g., such as that sold by T. C. Electronics as Model 1280DDL, but
such is merely exemplary. Thus, any type of delay can be used.
Each of the time delay circuits delays the input signal provided to it by
the predetermined period of time corresponding to the distance between the
main sound source and the associated zone and provides the delayed signals
via lines 38R and 38L to an associated transmitter subsystem. Thus, the
output lines 38R and 38L from time delay circuit 36-0 are provided as
inputs to the Channel 0 transmitter subsystem 30-0, the output lines 38R
and 38L from time delay circuit 36-1 are provided as inputs to Channel 3.
transmitter subsystem 30-1, and the output lines 38R and 38L from time
delay circuit 36-N are provided as inputs to Channel N transmitter
subsystem 30-N.
In accordance with a preferred aspect of this invention the respective
delayed signals from the unit 36 are equalized (e.g., their audio
frequency spectrum balanced) and dynamic level shaped (e.g., their
"dynamics" established) by means forming a portion of each of the
transmitter subsystems 30-0 to 30-N. Such means comprises an equalizer 40
of any suitable construction, such as a 1/3 octave equalizer sold by T. C.
Electronics as Model 1128, and a signal dynamic processor, e.g., an
expander, compressor, limiter, noise gate, etc., 42, but also of any
suitable construction. It should be pointed out at this junction that the
equalizer 40 and signal processor 42 are optional, and hence, one or both
may be eliminated from the system 20.
The delayed signals in each transmission subsystem are provided to an
associated wireless transmitter 44 therein for broadcast by an associated
antenna 46 connected to the output of the transmitter. The wireless
transmitter may be of any suitable construction for broadcasting a
electrical signal carrying the audio information, i.e., the audio signal
provided by the audio source 24. One exemplary wireless transmitter is
that sold by electrosonics as the T-72 Auditory Transmitter. That device
includes in it a signal dynamics processor and hence may also make up the
signal processor 42.
In the embodiment of FIG. 1 each of the respective transmitter subsystems
30-0 to 30-N of the system 20 is arranged to broadcast its associated
delayed signal at a different, preselected frequency for receipt by an
associated group of receiver/transducer subsystems located within a
predetermined zone in the arena or concert hall. In this regard, the
transmitter subsystem 30-0 broadcasts its delayed audio signal at one
predetermined frequency for receipt by the receiver/transducer
subsystem(s) 32-0 tuned to that one frequency and located within a first
zone in the concert hall, while the transmitter subsystem 30-1 broadcasts
its delayed audio signal at a second predetermined frequency for receipt
by the receiver/transducer subsystem(s) 32-0 tuned to that second
frequency and located within a second zone in the concert hall, and while
the transmitter subsystem 30-N broadcasts its delayed audio signal at an
Nth predetermined frequency for receipt by the receiver/transducer
subsystem(s) 32-N tuned to that Nth frequency and located within an Nth
zone in the concert hall.
Each of the receiver/amplifier units forming a portion of the
receiver/transducer subsystems 32-0 to 32-N is designated by the reference
number 48 and is preferably housed as a compact, easily portable unit.
Moreover, each unit 48 basically comprises an antenna 50, a wireless
receiver 52, a signal dynamics processor 54, an equalizer 56, and a power
amplifier 58. A portable electrical-to-acoustic transducer device is
associated with each unit to complete the receiver/transducer subsystem.
The transducer device may be any personal, and preferably readily portable
unit, e.g., a set of conventional stereo headphones 60, a personal
loudspeaker system 62, or any other suitable, small device, e.g., earpiece
transducers (not shown).
The wireless receiver 52 of each receiver/amplifier unit 48 is of
conventional construction and is arranged to be tuned to any of the
preselected frequencies being broadcast by its associated transmitter
subsystem. Thus, when the receiver is so tuned it takes the electrical
signal received on that frequency and converts it to electrical output
signals for driving the associated transducer device to replicate the
sound produced by the main sound source.
In accordance with a preferred aspect of this invention each of the
wireless receivers is arranged to be tuned to all of the frequencies being
broadcast by the various transmitter subsystems. Thus, each
receiver/amplifier unit can be used in any zone by merely tuning its
receiver to the frequency for that zone. To aid that tuning, each person
attending a concert where the system 20 of this invention is in use could
be given. instructions to tune. his/her receiver/amplifier unit 48 to a
particular channel setting based on seat numbers or sections (the
frequency of the transmission for that channel) so that the augmentation
sound and the main arrival sound arrive at his/her ears substantially in
synchronism.
Each receiver 52 includes a pair of output lines 64R and 64L which serve as
the inputs to the associated signal processor 54. Each signal processor 54
is of any suitable construction to provide the appropriate level dynamics
to the signals provided by the associated wireless receiver. The right and
left outputs of the signal processor 54 are provided as inputs to the
associated equalizer 56. Each equalizer 56 is also of any suitable
construction to achieve any desired frequency response modification. The
right and left outputs of the equalizer 56 are provided as inputs to an
associated power amplifier 58. The power amplifier may be of any suitable
construction for amplifying the input signals for provision to the
transducer device 60 or 62 associated with the receiver/amplifier unit 48.
The signal processor 54 and the equalizer 56 are each optional, and hence
the receiver/amplifier unit 48 need not include either or both of them. In
the later case the receiver/amplifier unit will merely comprise the
wireless receiver and an associated power amplifier. One exemplary
combined receiver, equalizer and amplifier is that sold by Lectrosonics as
the PRS-72 Auditory Receiver.
As will be appreciated by those skilled in the art means fox delaying the
input signal from the audio source, and for processing and broadcasting of
the delayed signal to the various receiver/amplifier units of the
receiver/transducer subsystems 30-0 to 30-N may be achieved in different
manners and using different means than that described above. For example,
such actions can be achieved within a single device rather than multiple
devices. Furthermore, the arrangement of the signal processing could be
reordered. Thus, the system shown and described with reference to FIG. 1
only reflects one current method of providing multiple time-delayed audio
signals for broadcast on particular channels.
The "manually synchronized" audio enhancement system will now be described
with reference to FIG. 2. Only the receiver/transducer subsystem of that
audio enhancement system is shown therein. This system is different than
the system of 20 of FIG. 1 in that it accomplishes synchronization of the
main arrival sound and augmentation sound by the user of the
receiver/amplifier unit manually adjusting time delay means (to be
described later) in his/her unit. This adjustment establishes the
necessary delay time of the electrical signal producing the augmentation
sound with respect to the main signal provided by the audio source so that
those sounds arrive in synchronism at the listener's ears. Thus, in the
"manually synchronized" sound enhancement system embodying FIG. 2 the
entire audience is covered by a single transmitter zone. In particular,
the audio signal is broadcast over a single frequency by a common, single
wireless transmitter (not shown in FIG. 2) to all of the
receiver/transducer subsystems located throughout the various zones in the
concert hall. That audio signal is provided from the audio source 24
described heretofore and may be processed by an equalizer and signal
dynamics processor also like that described heretofore prior to
transmission (broadcast).
Each of the receiver/transducer subsystems or units of the "manually
synchronized" audio enhancement system is of identical construction as the
others of that system. One exemplary construction of such a subsystem is
designated by the reference number 100 in FIG. 2. Like the
receiver/transducer subsystem of FIG. 1, the receiver/transducer subsystem
100 includes a receiver/amplifier unit 102 and an associated transducer
device, each of which is a compactly housed portable unit suitable for
easy carrying by a person
The receiver/amplifier unit 102 basically comprises an antenna 104, a
wireless receiver 106, a signal dynamics processor 42, a user adjustable
time delay 108, an equalizer 40, and a power amplifier 58. The signal
processor 42 and the equalizer 40 are constructed the same as and operate
in the same manner as those described earlier with respect to system 20.
Moreover, they are optional like in the system 20. The wireless receiver
106 is of any suitable construction and operates like wireless receiver 52
described heretofore except that it does not need to be tunable, i.e., it
can be pretuned to the frequency of the wireless transmitter. The power
amplifier 58 is constructed the same as and operates in the same manner as
that described earlier with respect to system 20. The user adjustable time
delay 108 can be of any suitable construction, e.g., analog or digital, to
delay the input signal provided to it from the wireless receiver 106 by a
selectable amount. To that end it includes manually operable means (not
shown), e.g., a rotatable knob and associated components, for adjusting
the amount of delay to be provided thereby. The adjustment may be in
discrete steps or may be continuous. In either case the user of the unit
102 could be instructed to set the amount of delay to a predefined
setting. That setting will have been predetermined to establish the
appropriate amount of delay based on the distance of the user's seat from
the main loudspeaker(s) or cluster(s). Alternatively, the user can be
instructed to adjust the manually operable means of the delay 108 until
the main sound and the augmented sound are in synchronism (this will be
readily determinable by the fact that the perceived sound will appear best
when the sounds are synchronized).
In FIG. 3 there is shown a receiver/transducer subsystem 200 forming a
portion of the "self-synchronized" audio enhancement system of this
invention. That system is like the "manually adjustable" system except
that instead of requiring manual adjustment by the user the adjustment
(synchronization of the augmentation sound and main sound) is accomplished
automatically by components within the system. To that end each
receiver/transducer subsystem 200 includes a compact, portable
receiver/amplifier unit 202, an associated portable transducer device,
e.g., headphones 60, and a sampling microphone 204 mounted on the portable
transducer device. The unit 202 includes means (to be described later) for
automatically adjusting the delay time in response to sound picked up by
the sampling microphone 204.
The receiver/amplifier unit 202 basically comprises a wireless receiver
106, a signal dynamics processor with a gating circuit 206, a programmable
delay circuit 208, an equalizer 40, a power amplifier 58, a programmable
control signal delay circuit 210, a signal gate 212, a microphone
preamplifier 214, a summing circuit 216, and a signal correlation circuit
218. The signal correlation circuit 218 itself comprises a correlate
circuit 220 and a controller 222.
The "signal processor" portion of the circuit 206 and the equalizer 40 are
constructed the same as and operate in the same manner as that described
earlier with respect to the signal dynamics processor and equalizer,
respectively, of the audio enhancement system 20. Moreover, they are
optional like in the system 20. In the implementation shown the "gate"
portion of the circuit 206 is not optional. Its structure and operation
will be described later. The wireless receiver 106 is of any suitable
construction and operates like wireless receiver of the "manually
synchronized" system described earlier. The power amplifier 58 is also
constructed the same as and operates in the same manner as that described
earlier with respect to system 20.
The programmable delay circuit 208 can be of any suitable construction,
e.g., analog or digital, to delay the input signal provided to it from the
signal processor portion of the circuit 206 in response to a control
signal provided by the signal correlation unit 218. The signal correlation
unit operates in response to sound received by the microphone 204 to
adjust the delay, so that the augmented sound provided by the headphones
will arrive at the user's ears in synchronism with main sound arriving
from the main loudspeaker(s) or clusters(s). In this regard the microphone
being located at the listening location, e.g., on the headphones 60 or
speaker system 62, gathers local sound pressure and provides an electrical
output signal via line 224 to the microphone preamplifier 214. The
microphone signal, after suitable amplification by the preamplifier 214,
is provided via a line 226 to one input of the gate 212. The gate 212 is
arranged when closed, as will be described later, to provide the amplified
microphone signal via line 228 to one input of the signal correlation unit
218. That signal correlation unit is also arranged to receive a signal via
line 230 from the output of the summing circuit 216. The summing circuit
is in turn arranged to receive the right and left delayed signals from the
programmable delay circuit via lines 232R and 232L to sum them and provide
the summed signal on line 230. The signal correlation circuit 218 utilizes
its correlate circuit 220 to correlate the amplified microphone signal
with the left and right sum of the delayed audio signal from the delay
circuit to provide an output signal on line 234 to be used by the
controller 222. The controller implements an algorithm to provide a
control signal on line 236 to the programmable delay 208. This signal
tunes the delay time to that which is appropriate for synchronizing the
augmentation sound with the main arriving sound.
Since the microphone is located within the sound field of the main
loudspeaker(s) or cluster(s) and will also inevitably be exposed to the
background ambient noise for best operation the receiver/transducer
subsystem 200 preferably includes some means to disable the microphone
during periods of no transmission, e.g., to prevent the output signal from
the microphone from being used to adjust the delay established by the
programmable delay, when the microphone in not in the presence of the main
arriving sound. This action effectively prevents local background noise,
such as crowd noise, from affecting control of the system.
One approach for disabling the microphone is the heretofore identified
signal gate 212 and the programmable control signal delay circuit 210. To
that end the signal gate 212 includes a control input provided by line 238
from the control signal delay circuit 210. That circuit receives a control
signal via line 240 from the "gate" portion of the signal processor and
gate circuit 206. In particular, if the audio input signals received by
the receiver 106 are not above a predetermined threshold the "gate"
portion of the signal processor and gate circuit 206 provides a control
signal indicative thereof to the programmable control signal delay circuit
210 That circuit in turn provides a gate control signal, via line 238, to
the signal gate 212. This action causes the signal gate to open to prevent
the amplified microphone signal on line 224 from being passed to the
signal correlation circuit 218. Once the input signals to the gate portion
of the signal processor and gate circuit 206 reach the threshold, such as
occurs when there is an audio signal provided by the audio source to the
main loudspeaker(s) or cluster(s), the output signal on line 240 will
cause the programmable control signal delay circuit 210 to provide an
enable signal on line 238. This action closes the gate 212 to enable the
microphone to effect control of the amount of delay provided by the
subsystem. Moreover, the sampled signal, i.e., the amplified microphone
signal, will only be present at the input to the signal correlation unit
for a short time before the main sound arrival at the listening location.
Hence using the actual program signal, this unit should, over time,
dynamically acquire the desired delay time at the listening location. It
should also be possible for it to track this delay time to any change in
listening location. Alignment signal bursts could also be broadcast from
the main signal source, the composition of which can be optimized for a
fast acquisition of the required delay Setting, rather than being part of
the actual audio program.
It must be pointed out at this juncture that the signal correlation
circuit, the summing circuit, and the programmable control signal delay
circuit can be implemented in various ways, e.g., via discrete components
or through by the use of a microprocessor with appropriate programming.
Moreover, in the disclosed embodiment the signal correlation unit
represents a electrical implementation of a mathematical function. The
exact implementation and function can change as other technologies
progress.
Without further elaboration the foregoing will so fully illustrate our
invention that others may, by applying current or future knowledge, adapt
the same for use under various conditions of service.
Top